Over one million acute myocardial infarctions (AMI) occur each year in the U.S. Percutaneous transluminal coronary intervention (PTCI) is the preferred treatment. Despite the overall effectiveness of PTCI, in the year following an initial heart attack, 30% of patients die. Animal and clinical studies have shown that whole-body cooling devices used together with PTCI can reduce heart-tissue damage compared to PTCI alone by 40-50%. These devices have two components, a cooling catheter that is placed in the inferior vena cava (IVC) and a cooling console that circulates coolant through the catheter. The catheter cools the whole-body by cooling the entire blood supply. As a result of the body's thermal inertia and thermoregulation system, achieving mild hypothermia (33C) takes 30 minutes to 1 hour. We are developing a new blood cooling catheter (CoolGuide) that delivers rapid focused cooling to the heart while leaving the rest of the body at normal temperature. CoolGuide aims to 1) simplify the cooling procedure, 2) reduce organ cooling time to under 5 min and 3) avoid whole-body cooling complications. A control console that circulates coolant and blood through the catheter will be part of the complete product. Catheter and console will be marketed together for use with PTCI. CoolGuide is a hybrid catheter, combining the functionality of existing guide catheters with the ability to provide cardioprotection with regional hypothermia. It uses a tri-lumen Teflon inner core, providing pathways for coolant flow and blood flow. Blood flows through the Coolguide directly into the coronary arteries. Phase I prototypes have demonstrated feasibility, using a large (70kg) pig model;these prototypes create regional mild hypothermia in 4-6 minutes. In Phase II we will optimize the Coolguide catheter and console, demonstrate hemocompatibility for the CoolGuide system during in vivo use with large swine, and demonstrate CoolGuide's ability to protect heart tissue. This in vivo data will be used to gain FDA approval for an initial human trial. Specific Aims:1.Design, build, and test refined CoolGuide prototypes for in vitro and in vivo testing, 2.Design, build, and test a refined CoolGuide console for in vitro and in vivo testing, 3.Test for hemocompatibility,4.Demonstrate the tissue salvage efficacy of the CoolGuide system (console and catheter) in large swine. The FDA has and will continue to provide guidance for CoolGuide in vivo testing. Relevance: The total cost associated with coronary disease is nearly 150 billion dollars. The fundamental challenge to improving patient outcome for heart attacks is minimizing ischemic tissue damage. This project seeks to harness a new therapeutic technology for focused organ cooling called CoolGuide to accomplish that goal. American Heart Association 2005 statistics show that in the first year following an initial heart attack, 25% of men and 38% of women die. Recent clinical studies have shown that mild whole body hypothermia (~34C) can salvage heart tissue after a heart attack. FocalCool, LLC seeks to develop a novel cooling catheter that cools heart tissue without the complications of whole-body cooling.